It was a bit muddled, in my eyes. Felt like they were trying to go for spooky and whimsical at the same time and neither melded well with the other, and it ended up feeling confused and messy. It got better as the episode went on, though.
Midnight still holds the top “spooky Dr Who episode”, imo, and I don’t expect it to be one upped easily. It’s so good.